Quick-seating piston ring and method of making the same



Jun@ 6, R933 W WUERFEL ET AL QUICK SEATING PIsIoN RIMG AND METHOD 0FMAKING THE SAME v Filed Aug, 6, 1928- 2 Sheets-Sheet l provide acylindrical outer surface w y upon a lathe with Patented .lune 6,

UNITEDl sTATEs PATENT ol-"Flcs WILLIAM'WUERFEI'., or' rmmnnima, ANDHAVILAND 111. rLAT'r, or WALLING'- FURD, PENNSYLVANIA, ASSIGNORS T0WILKENING MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, ACGRPORATION OF DELAWARE QUICK-SE'ATNG PISTON RING AND MEEHOD QF MARIN GrTHE SAME Application med august s, 192s. serial mi. 297,872.

Our invention relates to a new and useful method of finishing metallicsurfaces and it relates more particularly to anovel method of finishingthe peripheral or cylindrical contact surfaces of piston rings andthe-like.

It is the aim in making piston rings, particularly for internalcombustion engines, to

hich true and continuous circular contact against the cylinder wall, andwhich will. moreover, be capable of seating rapidly.

It has been the practice heretofore lto turn the outer cylindricalsurfaces of piston rings a relatively coarse turned finish so as toproduce u on such surface a slight, though apprecia le, spiral groove.

will present a When piston rings of this typeI are installed,

the initial contact is between a comparativel fine circular or spiralline at the top of t e groove, which wears off comparatively quickly asthe ring is seated against the inner surface of the cylinder.

In producing this comparatively coarse and quickly seating finish uponpiston rings, there is always an attendant disadvantage, in that thecoarse turned finish Vdoes not present a true or smooth circular contactedge initially, because'the top of the spiral groove is jagged or finelyserrated, and it has been found in practice that while thecoarse-finishturned rings seat comparatively quickly, they form a veryinefficient seal while seating; or prior to complete seating of thepiston. ring it is incapable of any considerable compression due to theserratedJ and hence discontinuous contacting edges on the outer'periphery of the ring.

It is the object of our Ainvention to roduce a piston ring of thecoarsely finis ed type, that is, a ring having a coarsely turned outersurface but which w1ll present continuous circular contacting edges whenfirst installed, thereby forming a igh pressure seal initially as wellas after the' ring has seated.

Thus, according to our invention, theouter' surfacesof piston ringsareturned Vin the usual manner, mounted upon a suitable mandrel in a lathe,and subsequent-to the final.A

`roll the tops or apices ofthe grooves into smooth and continuouscontact edges.

Our invention `also relates to a. novel tool for carrying out our novelmethod.

For the purpose of illustrating our invention we have shown in theaccompanying drawings one form thereof which is at present preferred byus, since the same has been found in practice to give satisfactory andreliable results, although it is to be understood that the variousinstrumentalities of which our invention consists can' be variouslyarranged and organized and that our invention is not limited to theprecise arrangement and organization of the instrumentalities as hereinshown and described.

In the accompanying drawings in Which like reference characters indicatelike parts:

Fi ure 1 represents a top plan Viety of piston rings mounted for turningin a lathe and the tool of our novel construction shown in operativerelation thereto. l Y

Figure 2 represents a side elevation of the same;

"Fi re 3 represents a section on line 3'-3 of Figure 1. y

Figure 4 represents of Figure 1.

v Figure 5 represents a top plan view of the tool holder, with arollerarm removed.

Y Figure 6 re resents a top plan view of the roller arman roller.

Figure 7 represents adiagrammatic, fragmentary, longitudinal section online 7-7 of Figure 1, on a greatly enlarged scale, showin the general`character of the coarse turne a section on line 4:-4

piston ringsurface prior to the rollingoperl ation.

Figure 8 represents a slmilar fragmentary diagrammatic sectional View online 8-8 of Figure 1, on a greatly enlarged scale, illustrating thegeneral character of the turned piston ring surface after the rollingoperap' l i tion. 4 y Figure 9 represents a similar diagrammaticsectional view on line 9-9 of i re 1, illustrating the serratedcharacter o the akof the turned groove prior to rolling,

and the smooth and continuous character of the same subsequent torolling.

In carrying out our novel method, the

lo the turned and rolled ringsl by the numeral 12.

i parallel ner, and ma be also sp it and rough turned 5 and clam ed upona sultable mandrel andon the outsi e. The rings are then mounted mountedetween centers on a suitable lathe, as shown schematically in Flgure 1.

Thus in'Figure 1, 10 designates the rings prior to final turning Whilethe inall turned rings are designate by the`numera 11 and The turningtoo.1 may be of any suitable character, as for instance, a tool bit '13mounted in a suitable tool holder 14as is commonly the practice.

In the preferred embodiment of the invention, the tool. holder 14 isprovided with a hollow internally and externally threaded stud or post15, through which the tool set screw l'extends. Upon the tubular stud orpost 15 a resilient or spring roller-arm 17 is mounted, as shownparticularly in Figures 1`, 3 and 6; the roller arm 17 being providedwlth `a terminal eyelet 18 which fits over the stud 15. A keyway slot 19is cut into the eyelet 18, while the upper shoulder 20 of the toolYholder `is provlded with a fixed key 21, adapted to seat within thekeyway or slots 19 in the e elet 18 of the roller arm, thereby to retaintile same against turning or deflection upon the tool holder. A nut 22threaded onto the stud 15 clamps the roller arm 17 firmly to the toolholder.

The roller arm 17 is suitabl vshaped kso that the free end 23 thereofwil be substantially parallel to the direction of travel vof the `lathecarriage, and so that it' will be suiiiciently resilient and yielding.

Upon the free end 23 of the spring arm 17, a roller 24 is mounted in amanner shown particularly in Figure 4. Thus the roller 24 is carriedupon a suitable roller bearing 25 and upon a fixed stationary screw 26threaded into the end of the arm 23. The

roller 24 is preferably of some extremely hard steel or alloy and isprovided with a slightly rounded peripheral nose 27 which contacts withthe work.

In settin up the machine, the tool bit 13 is set slight y further backthan the roller 24 so that'when thev transverse carriage of the lathe isadvanced towards the work the roller will contact with the work first bya suitable amount, and as the carriage is further advanced to brin thetool bit to the proper diameter of the nished ring, the roller 24carried by the resilient spring arm 17 will be deflected back .a slightextent, thereby imparting suitablefpressure to the roller. The pressureon the roller may be varied by suit- `ablytadjusting the tool bit 13with respect to the finished diameter of the piston rings and withrespect to the roller 24.

Figure 7 represents a greatly magnified transverse section of a ringafter it has been turned to the desired finished diameter by the toolbit 13. The turned surface thus consists of a continuous helical groove28, the bottom 29 of which may be of any suitable shape, dependeningupon'the shape of the ltip of the tool bit 13, while the top 30 of thegroove is a comparatively line line edge. Due to the lslightvibration ofthe tool bit 13 and `possibly also 'due to the extreme iineness of theedge 30, said edge does not present a smooth and continuous circle butis somewhat uniformly serrated or jagged as indicated schematically inFigures 2 and 9.

As the roller 24 passes over the groove 28, it depresses and re-shapesthe top of the groove to a-somewhat flattened and smooth edge 31,indicated in Figures 8 and 9.

The resultant rolled-finished surface is thus like-wise composed of acontinuous helical groove, but having a smooth continuous up per edgelying generally in a circle. A piston ring thus produced will possesstheinherent advantage over the rings heretofore made, in that it willnot only seat quickly, but it will also form a pressure-proof sealduring the time requiredA for seating, since even the ine contact lineof the groove of the coarse finished surface will form a pressure-proofseal against a cylindrical surface because the normal irregularities orserrations thereof have been removed by the rolling operation.

We are awareJthat our invention may be embodied in otherspecific formsWithout departing from the spirit or essential attributes thereo and wetherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive, reference being had to the appendedclaims rather than to the foregoing description to indicate the scope ofthe invention.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent, is

1. The method of finishing piston rings which consists in turning theouter cylindrical surface of the piston ring with a relatively-coarsecut, to a diameter slightly in excess of the desired linished diameterand producing thereby, upon'said outer cylindrical surface, a slightspiral ridge having contiguous convolutions, and pressing down the topof said ridge to a suitable extent in a generally longitudinal directionwith respect thereto, without however obliterating the same.

2. The method of finishing cast iron piston rings, which consists inturning the outer cylindrical surface of the piston ring with arelatively coarse cut, to the diameter slightly in excess of the desiredfinished-diameter ,and producing thereby, upon said outer cylindricalsurface, a slight spiral ridge having contiguous convolutions, andsubsequently rolling down the top of said ridge to a suitable extent ina generally longitudinal direction with respect thereto, without howeverobliterating the same.

3, A qu1ck-seati`ng piston ringv having itsouter cylinder-contactsurface coarsely turned with a slight spiral groove and correspondingslight' spiral ridge extending over its cylinder-contact surace;-saidslight spiral ridge being slightly rolled downto a {suitable extent,without however being obliterated;` said slightly coarse-turned androlled-down spiral ridge being adapted to be worndown first in theinitial 4operation of thepiston ring Within a cylinder, thereby 'morequickly to obtain a pressure-sealing fit y between the cylinder wall andthe piston ring, in the early life of the latter.

. WILLIAM WUERFEL.

HAVILAND H: PLATT.

